1. Field of the Invention
The present invention relates to a polymeric solid electrolyte.
2. Related Art
In recent years, solid electrolytes are attracting attention to obtain various electrochemical devices in the form of solid. Solid electrolytes known previously include polyethylene oxide (hereinafter referred to as PEO), vinyl polymers having PEO in the side chain and polymeric solid electrolytes formed by addition of a salt to siloxane polymers. Further, a solid electrolyte has been proposed which is obtained by impregnating a crosslinked polymer having a high ionic conductivity with an electrolyte solution.
However, the above-mentioned polymeric solid electrolytes comprising PEO have a glass transition temperature not lower than room temperature; they do not always have a sufficiently high ionic conductivity in the neighborhood of room temperature, and mostly have an insufficient flexibility. Therefore, solid electrolytes of this kind which have a high ionic conductivity at low temperatures and have a satisfactory mechanical strength have been awaited. Vinyl polymers having PEO in the side chain have a problem in attaining a low-cost commercial production, because a vinyl monomer having PEO must be synthesized therefor. In the solid electrolyte obtained by impregnation with an electrolyte solution, such problems as liquid spill, etc. have been pointed out.